C++/Map Multimap/multimap insert
Insert value pair to int, double multimap
#include <iostream>
using std::cout;
using std::endl;
#include <map>
int main()
{
std::multimap< int, double, std::less< int > > pairs; // declare the multimap pairs
cout << "There are currently " << pairs.count( 15 )
<< " pairs with key 15 in the multimap\n";
// insert two value_type objects in pairs
pairs.insert( std::multimap< int, double, std::less< int > >::value_type( 15, 2.7 ) );
pairs.insert( std::multimap< int, double, std::less< int > >::value_type( 15, 99.3 ) );
cout << "After inserts, there are " << pairs.count( 15 )
<< " pairs with key 15\n\n";
cout << endl;
return 0;
}
/*
There are currently 0 pairs with key 15 in the multimap
After inserts, there are 2 pairs with key 15
*/
load the user-defined objects from vector into the multimap
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <string>
#include <utility>
#include <vector>
using namespace std;
class PC
{
public:
enum PC_type { Dell, HP, IBM, Compaq };
PC( PC_type appliance = Dell, int model = 220,
int serial = 0 );
bool operator<( const PC& rhs ) const;
PC_type appliance() const;
int model() const;
string name() const;
void print() const;
int serial() const;
private:
PC_type appliance_;
int model_;
int serial_;
};
inline
PC::PC( PC::PC_type appliance, int model,
int serial )
: appliance_( appliance ), model_( model ), serial_( serial )
{}
inline
bool PC::operator<( const PC& rhs ) const
{ return appliance() < rhs.appliance() ||
( appliance() == rhs.appliance() && model() < rhs.model() );
}
inline
PC::PC_type PC::appliance() const
{ return appliance_; }
inline
int PC::model() const
{ return model_; }
string PC::name() const
{
string what;
switch( appliance() )
{
case Dell: what = "Dell"; break;
case HP: what = "HP"; break;
case IBM: what = "IBM"; break;
case Compaq: what = "Compaq"; break;
default: what = "Unknown appliance"; break;
}
return what;
}
inline
void PC::print() const
{
char oldfill = cout.fill();
cout << name() << " - Model "
<< model() << ", Serial number "
<< serial() << endl;
}
inline
int PC::serial() const
{ return serial_; }
bool greater_model( const pair<PC::PC_type,PC> p,int min_model );
int main( )
{
const PC::PC_type kind[] = { PC::IBM,
PC::IBM, PC::Dell, PC::HP,
PC::HP, PC::HP };
const int num_appliances = 3;
vector<PC> v;
for( int i = 0; i < num_appliances; ++i )
v.push_back( PC( kind[i], i, i ) );
map<int,PC> sold;
transform( kind, kind+num_appliances, v.begin(),inserter( sold, sold.end() ),make_pair<int,PC> );
map<int,PC>::const_iterator sold_end = sold.end();
map<int,PC>::const_iterator site;
for( site = sold.begin(); site != sold_end; ++site )
site->second.print();
// work with a multimap. key is appliance type, value is PC
typedef multimap<PC::PC_type,PC> PC_multimap_type;
PC_multimap_type stock;
// appliance that customer desires
const PC desired( PC::HP );
cout << desired.name();
// load the appliances into the multimap
transform( kind, kind+num_appliances, v.begin(),inserter( stock, stock.end() ), make_pair<PC::PC_type,PC> );
PC_multimap_type::const_iterator stock_end = stock.end();
}
inline
bool greater_model( const pair<PC::PC_type,PC> p,int min_model )
{ return p.second.model() >= min_model; }